| 河南登封石牌河“变闪长岩体”的锆石SHRIMP年代学研究 |
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| 关键词:Shipaihe “metadiorite” SHRIMP TH/U ratio geological event |
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| SHRIMP U-Pb Zircon Geochronology of the Shipaihe "Metadiorite Mass" from Dengfeng County, Henan Province |
| The Shipaihe “metadiorite mass” from Dengfeng County of Henan Province is composed of diorite-tonalite and granodiorite, which are fractionation products of the same magmatic series. The emplacement or crystallization age of igneous mass determined previously by zircon isotopic analysis is 2 520±17 Ma. However, recent SHRIMP U-Pb analysis of the same zircons yield a new age of 2 493±7 Ma. The Th/U ratios of zircons range from 0.76 to 1.27, with the average value being 1.03. All the zircons are characterized by distinct magmatic zoning, and their crystal centers and rims have the same age. These features indicate that the zircons are of magmatic type not subjected to metamorphism, and hence the above new SHRIMP U-Pb zircon data may represent the crystallization or emplacement age of Shipaihe “metadiorite mass”. According to characteristics of field geology, petrology and geochemistry, the Shipaihe “metadiorite mass” is very similar to the same type of rock in Taishan Complex of west Shandong Province. They are both products of late Neo-Archean in spite of their slight difference in ages. The extensive diorite-granite magmatism and regional metamorphism related to tectonism suggest the existence of an important geological-tectonic event in the late period of Neo-Archean. |
| WANG Ze-jiu,SHEN Qi-han,WAN Yu-sheng.2004.SHRIMP U-Pb Zircon Geochronology of the Shipaihe "Metadiorite Mass" from Dengfeng County, Henan Province[J].Acta Geoscientica Sinica,25(3):295-298. |
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